rammtd:add rammtd_uninitialize

Summary:
  Added rammtd_uninitialize to manage rammtd

Signed-off-by: chenrun1 <chenrun1@xiaomi.com>

drivers/mtd/rammtd.c

@@ -520,3 +520,21 @@ FAR struct mtd_dev_s *rammtd_initialize(FAR uint8_t *start, size_t size)
 
   return &priv->mtd;
 }
+
+/****************************************************************************
+ * Name: rammtd_uninitialize
+ *
+ * Description:
+ *   Free the resources associated with a RAM MTD device instance.
+ *
+ * Input Parameters:
+ *   dev - Pointer to the MTD device instance to be uninitialized.
+ *
+ ****************************************************************************/
+
+void rammtd_uninitialize(FAR struct mtd_dev_s *dev)
+{
+  FAR struct ram_dev_s *priv = (FAR struct ram_dev_s *)dev;
+
+  kmm_free(priv);
+}

include/nuttx/mtd/mtd.h

@@ -490,6 +490,19 @@ FAR struct mtd_dev_s *mx35_initialize(FAR struct spi_dev_s *dev);
 
 FAR struct mtd_dev_s *rammtd_initialize(FAR uint8_t *start, size_t size);
 
+/****************************************************************************
+ * Name: rammtd_uninitialize
+ *
+ * Description:
+ *   Free the resources associated with a RAM MTD device instance.
+ *
+ * Input Parameters:
+ *   dev - Pointer to the MTD device instance to be uninitialized.
+ *
+ ****************************************************************************/
+
+void rammtd_uninitialize(FAR struct mtd_dev_s *dev);
+
 /****************************************************************************
  * Name: ramtron_initialize
  *